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      <title>限流算法（令牌桶漏桶） - 交互式测验</title>
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      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>限流算法（令牌桶漏桶） - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档描述，令牌桶（Token Bucket）和漏桶（Leaky Bucket）算法在处理突发流量（bursts of traffic）时，其核心区别是什么？",
    "options": [
      "漏桶算法能够处理突发流量，而令牌桶算法会将流量平滑化。",
      "令牌桶算法允许在令牌充足的情况下处理突发流量，而漏桶算法则强制以恒定的速率处理请求，从而平滑化流量。",
      "两种算法都无法处理突发流量，会直接拒绝超出速率的请求。",
      "令牌桶算法处理请求的速率是固定的，而漏桶算法的速率则根据突发流量动态调整。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "令牌桶的核心优势在于其灵活性。只要桶内有足够的令牌，它就可以应对短时间内超过平均速率的突发请求，这对于需要快速响应但又需要整体速率可控的场景非常有用。相比之下，漏桶的流出速率是恒定的，它会将所有进入的请求（无论多么突然）都整形为平滑、匀速的流量，起到了“削峰填谷”的作用。",
    "source": "文档中「令牌桶」和「漏桶」的解题思路部分",
    "hint": "思考一下哪个算法是“积攒权限以便未来使用”，而哪个算法是“强制以固定速度输出”。"
  },
  {
    "question": "在文档提供的令牌桶（Token Bucket）示例代码中，当一个`TokenBucket`对象被实例化时，桶内的初始令牌数（`tokens`）是多少？",
    "options": [
      "0",
      "等于令牌生成速率（rate）",
      "等于桶的容量（capacity）",
      "1"
    ],
    "correctAnswerIndex": 2,
    "explanation": "在`TokenBucket`的构造函数中，有这样一行代码：`this.tokens = capacity;`。这意味着系统在启动之初就被认为是“准备就绪”的，可以立即处理最多相当于桶容量的突发请求，而无需等待令牌的生成。",
    "source": "文档中「示例代码」（令牌桶）",
    "hint": "请查看`TokenBucket`类的构造函数部分，找到`tokens`变量被初始化的那一行代码。"
  },
  {
    "question": "根据漏桶（Leaky Bucket）算法的描述和示例代码，当一个新请求到达但桶已满时（`water >= capacity`），系统会如何处理这个请求？",
    "options": [
      "暂时提高流出速率（rate）以腾出空间。",
      "将请求放入一个备用队列等待。",
      "拒绝该请求。",
      "自动擴大桶的容量（capacity）。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "漏桶算法的核心思想之一是容量有限。文档的“解题思路”中明确指出“若桶满则丢弃请求”。在示例代码中，只有当`water < capacity`时，请求才会被接受并使`water++`，否则`allowRequest()`方法将返回`false`，意味着请求被拒绝。",
    "source": "文档中「漏桶」的解题思路和「示例代码」（漏桶）",
    "hint": "文档中有一句关键描述：“若桶满则丢弃请求”。"
  },
  {
    "question": "在令牌桶（Token Bucket）的`allowRequest()`方法实现中，新令牌是何时被计算并添加到桶里的？",
    "options": [
      "由一个独立的后台线程定时添加。",
      "仅在令牌数量降为零时触发添加。",
      "在每次有新请求调用`allowRequest()`方法时，根据距离上次调用的时间差来计算并添加。",
      "只在构造函数初始化时添加一次。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "令牌桶算法采用的是一种“懒计算”策略。系统不会主动、持续地去更新令牌数。而是在每次请求到达时，根据当前时间与`lastRefillTime`的时间差，动态计算出这段时间内应该生成多少新令牌，然后更新桶内令牌数。这样做既高效又精确。",
    "source": "文档中「示例代码」（令牌桶）",
    "hint": "观察`allowRequest()`方法内部的逻辑，令牌的计算`newTokens = (now - lastRefillTime) / 1000.0 * rate;`是在方法被调用时执行的。"
  },
  {
    "question": "文档中对令牌桶算法的时间复杂度和空间复杂度有明确的描述，它们分别是什么？",
    "options": [
      "时间复杂度：O(n)，空间复杂度：O(n)",
      "时间复杂度：O(log n)，空间复杂度：O(1)",
      "时间复杂度：O(1)，空间复杂度：O(1)",
      "时间复杂度：O(1)，空间复杂度：O(n)"
    ],
    "correctAnswerIndex": 2,
    "explanation": "令牌桶算法的每次`allowRequest()`调用都只涉及几次数学计算和变量更新，其执行时间不随请求数量的增加而改变，因此时间复杂度是O(1)。同时，该算法只需要固定的几个变量（如capacity, tokens, rate, lastRefillTime）来维持状态，不需额外的存储空间来记录请求历史，因此空间复杂度也是O(1)。",
    "source": "文档中「令牌桶」的解题思路部分",
    "hint": "在文档对令牌桶的文字描述部分，直接提到了这两个复杂度指标。"
  },
  {
    "question": "在令牌桶的示例代码中，使用`Math.min(capacity, tokens + newTokens)`来更新令牌数量。这一步操作的主要目的是什么？",
    "options": [
      "防止因`tokens`值过大导致内存溢出。",
      "确保令牌的生成速率不会超过预设的`rate`值。",
      "确保桶中的令牌数量永远不会超过其设定的最大容量（capacity）。",
      "提高浮点数计算的精度。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "桶的“容量”是令牌桶算法的一个关键限制。即使系统在很长一段时间内没有请求（导致计算出的`newTokens`非常大），累积的令牌数也不能无限增长。`Math.min()`函数确保了无论计算出多少新令牌，最终存储的令牌总数都不会超过`capacity`这个上限，这符合令牌桶的定义。",
    "source": "文档中「示例代码」（令牌桶）",
    "hint": "想一想“桶”这个比喻，它的主要物理特性之一是什么？"
  },
  {
    "question": "漏桶算法的核心工作机制是什么？",
    "options": [
      "以固定速率生成处理许可（水滴），请求消耗许可后才能被处理。",
      "将到达的请求放入一个队列（桶），并以一个恒定的速率从队列中取出并处理请求。",
      "根据请求的优先级动态调整处理速率。",
      "当请求量大时，自动增加桶的容量以缓存更多请求。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "漏桶算法就像一个顶部进水、底部匀速漏水的桶。请求（水）进入桶中，而系统以一个固定的速率（漏水速率）处理这些请求。这种机制的直接效果是，无论进入的流量波动多大，流出的流量总是平滑且速率恒定的。",
    "source": "文档中「漏桶」的解题思路部分",
    "hint": "文档描述为：“请求以固定速率流出”。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

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          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
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          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
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            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
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                    li.classList.add('selected');
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            optionsListEl.appendChild(li);
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          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
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          updateNavigationButtons();
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        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
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            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
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        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
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        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
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                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  